public class Demo9 {
    private static boolean flag=true;
public static void main(String[] args) {
    Thread t=new Thread(()->{
    while(flag){
        System.out.println("hello thread");
    try{
         Thread.sleep(1000);
    } 
    catch(InterruptedException e){
        e.printStackTrace();
    }
}
    });
    t.start();    
    System.out.println("hello main");
    try {
        Thread.sleep(3000);
    } catch (InterruptedException e) {
        e.printStackTrace();
    }
    flag=false;
    System.out.println("让t线程结束");
}
}
